Cardiac CT Angiography After Coronary Bypass Surgery: Prevalence of Incidental Findings

Jeffrey Mueller 1,2 ; Jean Jeudy 1 ; Robert Poston 3 ; Charles S. White 1

1 Department of Diagnostic Radiology, University of Maryland School of Medicine, 22 S Greene St., Baltimore, MD 21201.
2 Present address: Department of Radiology, Allegheny General Hospital, Pittsburgh, PA.
3 Division of Cardiac Surgery, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD.

OBJECTIVE: Cardiac CT angiography (CTA) is commonly performed after coronary artery bypass grafting surgery (CABG) to assess graft patency, but the images also include parts of the lungs, abdomen, and mediastinum. The purpose of our study was to retrospectively assess the prevalence of unsuspected disease identified on cardiac CTA examinations after CABG and to determine their potential clinical significance.

MATERIALS AND METHODS: CTA was performed postoperatively in 259 patients (mean, 5.2 days), and 40 patients underwent a follow-up CT scan (mean, 12.7 months). Cardiac CTA was acquired using a 16-MDCT scanner with ECG-gating and bolus timing with a small field of view centered on the heart. Two thoracic radiologists assessed each examination in consensus. The prevalence of graft disease and incidental findings (cardiac and noncardiac) was established. The electronic medical record was reviewed. A finding was judged potentially significant if a therapeutic intervention or radiologic follow-up was deemed advisable on the basis of the cardiac CTA. Bypass graft occlusions were analyzed separately.

RESULTS: In the immediate postoperative period, 51 patients (19.7%) had at least one unsuspected, potentially significant finding. Twenty-four patients (9.3%) had a cardiac finding such as a ventricular pseudoaneurysm, ventricular perfusion deficit, or intracardiac thrombus, and 34 patients (13.1%) had a noncardiac finding including pulmonary embolism, lung cancer, or pneumonia. At least one bypass graft was occluded in 17 patients (6.6%) in the immediate postoperative period. In the later postoperative period, seven patients (17.5%) had a potentially significant unsuspected finding. Four patients (10.0%) had at least one graft occlusion.

CONCLUSION: Cardiac CTA after CABG revealed a high prevalence of unsuspected cardiac and noncardiac findings with potential clinical significance. Interpreters of these studies should be familiar with the spectrum of these abnormalities.